1. Field of the Disclosure
The disclosure relates to a method for producing a shaped glass article having a predefined geometry without using a mold, and further relates to the use of the glass article produced according to such method, and to a shaped glass article.
2. Background of the Disclosure
In some current processes, molds are employed for forming glass articles from flat glass, and the glass article will contact the mold towards the end of molding.
United States Patent Application Publication Nos. 2010/0107525 A1 and 2013/0321903 A1 discuss vacuum insulated glazing, in which bumps are formed in the surface of one of the glass panes of the vacuum insulated glazing. These bumps serve as spacers between the glass panes. The bumps are caused by density and volume changes in the glass by local heating. A drawback hereof is that mechanical stresses may be caused in the glass due to the volume change.
Methods for patterning glass surfaces are furthermore known from U.S. Pat. Nos. 5,567,484 A, 5,978,189 A, 6,391,213, and 6,664,503 A. All these methods relate to the patterning of glass sheets for magnetic or optical data storage media. According to U.S. Pat. No. 5,567,484 A, bumps are produced by laser irradiation for this purpose, similar as in the above citations relating to insulated glazing. The problem of mechanical stresses is addressed therein by a narrow process window in terms of laser pulse power. By contrast, according to U.S. Pat. No. 5,978,189 A, patterning is accomplished on the basis of evaporation of the glass material. According to U.S. Pat. No. 6,391,213 A, bumps or webs are first produced using a laser, which are preferentially attacked in a subsequent etching step, so that indentations are obtained at the locations of the bumps. According to U.S. Pat. No. 6,664,503 A, such similarly produced linear indentations are used as breaking lines to tailor glass sheets to the formats desired for data storage media.
According to European Patent Publication No. 0690028 A1 and United States Patent Application Publication No. 2003/209040 A1, a method for producing bumps by heating the glass is used for producing microlenses.
United States Patent Application Publication No. 2010/0000259 A1 substantially describes the bending of glasses preferably by using medium-wave IR radiation that is preferentially absorbed in the glass.
German Patent Application DE 10 2010 020 439 A1 discloses several methods for deforming individual glass articles, inter alia with the use of a mold and by selecting different temperatures at different points of the glass molding.
United States Patent Application Publication No. 2012/0114901 A1 describes a method for producing cover glasses, in which individual sheets are bent with an appropriately chosen temperature distribution and appropriately chosen radii of the mold.
The forming process is terminated as soon as the product contacts the mold over its entire surface.
International Patent Publication No. WO 2011/000012 A1 describes laser-heated bending pressing of materials.
All these methods either require molds of excellent surface quality which are very complicated and expensive to manufacture, or require reworking by grinding and polishing, which results in high complexity and high costs.
German Patent Application No. DE 10 2011 050628 A1 describes a bending method that does not use a mold, however, in this case the radiation sources are configured as radiant burners which have to be re-positioned mechanically depending on the desired bending geometry.
German Patent Application No. 10 2007 012146 B4 describes a laser beam and a scanning mirror for locally raising the temperature in the glass sheet to be deformed and to deform it through the action of gravity. In this case, temperature measurement is required since the deformation is directly controlled by the viscosity which is directly related to the temperature.
In case of thin flat glasses and small areas to be deformed it has been found by following the instructions of German Patent Application No. DE 10 2007 012146 B4 that gravity alone is no longer sufficient for deformation, since the surface tension causes the glass to keep its shape.
From International Patent Publication No. WO 2005/042420 A1, a method is known for producing a glass molding having a polygonal plate-shaped and optionally at least partially bulging base and at least one leg which is bent back along an edge of the base, comprising the steps of:                providing a polygonal flat, optionally at least partially bulging glass pane;        heating the edge on at least one side of the glass pane to the softening point of the glass using a linear burner;        bending the glass rim which protrudes beyond the low-viscosity edge along the bending edge to a predefined angle as a leg of the glass molding;        cooling the glass molding.        
German Patent Application No. DE 38 37 552 A1 describes a method for producing a glass product having a smooth surface, wherein a glass plate is placed on a male mold which has dimensions corresponding to the inner dimensions of the glass product, so that the male mold contacts the inner peripheral edge portion of the glass plate. The outer peripheral portion to be deformed of the glass plate is heated to a temperature which is greater than that of a central portion of the glass plate, so as to be deformed on the male mold by its own weight. The glass plate deformed in this way is pressed by a female mold whose dimensions correspond to the external dimensions of the glass product.
International Patent Publication No. WO 2013/055587 A1 also discloses a method for deforming a flat glass.